Though, wouldn't fade in be a good way of training your reaction time in a way? Just as hidden is a good way of training your accuracy.I use FL for reaction time training. That and the fact that I read at pretty high speeds. I read 150 BPM at speed 18 now. I usually play FL at about speed 10, for most stuff which really doesn't leave that much time to react.
Just a thought.
I've got a habit of looking lower on the screen than I should, so Hidden forces me to look higher, which gives me more time to react to things.